<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title>Document</title>
		<style>
		#airplane{
			position: absolute;
			width: 66px;
			height: 80px;
			left: 600px;
			top: 700px
		}
		body{
			background: url(image/background_1.png);
		}
		#clip div{
			width: 6px;
			height: 14px;
			background: url(image/bullet1.png);
			position: absolute;
			left: 50px;
			top: 50px;
		}
		#enemy div{position: absolute;}
		</style>
		<script src = "tool.js"></script>
		<script>
		window.onload = function(){
			drag($("#airplane"));

			Gatlin(4);

			sneer(1);

		}

		/*
			================================
			敌机的创建

		*/
		function sneer(num){
			setInterval(createEnemy, 1000 / num)
		}
		var arr = [{
			img: "image/enemy2_fly_1.png",
			width: "110px",
			height: "164px",
			HP: 3,
			beat: "image/大飞机挨打.png",
		}, {
			img: "image/enemy3_fly_1.png",
			width: "46px",
			height: "60px",
			HP: 2,
			beat: "image/中飞机挨打.png"
		}, {
			img: "image/enemy1_fly_1.png",
			width: "34px",
			height: "24px",
			HP: 1,
			beat: ""
		}]

		function createEnemy(){

			//随机飞机
			var index = Math.floor(Math.random() * 3);

			//通过飞机的信息创建飞机
			var oEnemy = document.createElement("div");
			var oImg = document.createElement("img");
			oImg.src = arr[index].img;
			oEnemy.appendChild(oImg);
			oEnemy.style.width = arr[index].width;
			oEnemy.style.height = arr[index].height;
			oEnemy.HP = arr[index].HP;
			oEnemy.beat = arr[index].beat;
			$("#enemy").appendChild(oEnemy);

			//设置敌人出现坐标
			var X = parseInt(Math.random() * (document.documentElement.clientWidth - oEnemy.offsetWidth));
			var Y = oEnemy.offsetHeight;

			oEnemy.style.left = X + "px";
			oEnemy.style.top = -Y + "px";


			//敌人从上往下掉 
			var target = document.documentElement.clientHeight - oEnemy.offsetHeight;
			startMove(oEnemy, target, function(){
				$("#enemy").removeChild(oEnemy);
			});

		}

		/*
			==================================
			Gatlin
		*/
		function Gatlin(num){
			var aBulltes = $("#clip").getElementsByTagName("div");
			//给每一颗子弹设置一个布尔值，布尔值是，指示当前子弹是否正在飞
			for(var i = 0; i < aBulltes.length; i++){
				//初始状态所有子弹的飞行状态都是false
				aBulltes[i].isrunning = false;
			}
			setInterval(function(){
				var node = load(aBulltes);
				if(node){
					fire($("#airplane"), node);
				}
				
			}, 1000 / num);
		}

		/*
			子弹 -> 上膛（找出一颗可以飞的子弹进行发射）
		*/
		function load(aBulltes){
			for(var i = 0; i < aBulltes.length; i++){
				//找出没有在飞的子弹发射, isrunning = false;
				if(!aBulltes[i].isrunning){
					return aBulltes[i];
				}
			}
		}

		function fire(oAirPlane, oBullte){
			oBullte.isrunning = true;
			//1、确定枪口的位置
			var X = oAirPlane.offsetLeft + oAirPlane.offsetWidth / 2 - oBullte.offsetWidth / 2;
			var Y = oAirPlane.offsetTop - oBullte.offsetHeight - 2;
			//2、需要将子弹挪动到枪口位置
			oBullte.style.left = X + "px";
			oBullte.style.top = Y + "px";


			/*
				当子弹废除屏幕的时候，子弹完成了使命。
				子弹完成了使命，我们就将子弹拿回来复用。
			*/
			startMove(oBullte, -14, function(){
				oBullte.isrunning = false;
			});
		}

		/*
			1、定时器没有关闭
			2、他没有到达目的值
		*/

		// var timer = null;
		//给每一个子弹配一个单独的定时器
		function startMove(obj, iTarget, func){
			clearInterval(obj.timer);
			obj.timer = setInterval(function(){
				var speed = 0;
				if(obj.offsetTop > iTarget){
					speed = -5;
				}else{
					speed = 5;
				}
				if(Math.abs(obj.offsetTop - iTarget) < Math.abs(speed)){
					clearInterval(obj.timer);
					//挪动到目的值
					obj.style.top = iTarget + "px";

					if(func){
						func();
					}
				}else{
					obj.style.top = obj.offsetTop + speed + "px";
					/*
						=================================
						碰撞检测
					*/
					//判断当前obj是敌人，判断敌人和我方飞机发生碰撞，将我发飞机爆炸
					if(obj.parentNode.id == "enemy" && crash(obj, $("#airplane"))){

						$("#airplane").firstElementChild.src = "image/本方飞机爆炸.gif";
						alert("GAME OVER");
						location.reload();
						
					}

					//判断敌人和子弹是否发生碰撞
					var aEnemys = $("#enemy").getElementsByTagName("div");
					for(var i = 0; i < aEnemys.length; i++){
						if(obj.parentNode.id == "clip" && crash(obj, aEnemys[i])){
							//敌人消失  子弹消失 子弹应该去复用
							obj.style.top = -obj.offsetTop + "px";
							obj.isrunning = false;
							if(aEnemys[i] && aEnemys[i].HP == 1){
								$("#enemy").removeChild(aEnemys[i]);
							}else{
								aEnemys[i].firstElementChild.src = aEnemys[i].beat;
								aEnemys[i].HP--;
							}
						}
					}

				}
			}, 20)
		}
		</script>
	</head>
	<body>
		<div id = "airplane">
			<img src = "image/我的飞机.gif" ondragstart = "return false"/>
		</div>
		<div id = "clip">
			<div></div>
			<div></div>
			<div></div>
			<div></div>
			<div></div>
			<div></div>
			<div></div>
			<div></div>
			<div></div>
			<div></div>
			<div></div>
			<div></div>
		</div>
		<div id = "enemy"></div>
	</body>
</html>















